The diagrams below show the development of the horse over a period of 40 million years. Summarise the information by selecting and reporting the main features, and make comparisons where relevant.

The diagrams demonstrate the changes in sizes and shapes between prehistoric and modern horses from 40

million

years

ago to today.

In addition

, these photographs

also

describe the evolutionary stages of their

feet

during

this

given period. In general, throughout history, the

size

of horses has increased gradually, and the structure of their

feet

has become simpler to adapt to new environmental habitats.

According to

the data, the original

horse

, Eohippus, existed 40

million

years

ago. These creatures were small, and their tails were short at the time, with four slender toes on each foot. Over the following 10

million

years

, the descendants of Eohippus, called Mesohippus, emerged, owning a bigger

size

and longer tails than their ancestors. Notably, Mesohippus’

feet

had only three digits on each foot. Approximately 15

million

years

ago, the presence of Merychippus was recorded. These wild animals were taller, and their mane was thicker than the two former species.

Moreover

,

although

the structure of the

feet

was similar to that of the Mesohippus, the

size

was bigger, specifically the middle toe.

Finally

, the modern

horse

, known as the

last

transformation, had the biggest

size

among others. With a sturdy single hoof and strong structure of bone, they contributed to an erect posture for

this

kind of

horse

.

Additionally

, because of the change in DNA, it was found that there was more hair on the mane and tail of the modern

horse

.